This invention relates to a transmission lubricating device which supplies transmission oil selectively to high-speed and low-speed gearing in the transmission, depending on engine speed.
A transmission, or a similar device, is used in a vehicle to supply a force from the vehicle's engine to the wheels that depends on the driving conditions. The transmission can be set to one of several settings or "speeds". The transmission includes an input shaft and a counter shaft situated in parallel. For each speed of the transmission, an input gear on the input shaft engages a corresponding counter gear on the counter shaft. A final drive gear, mounted at the end of the counter shaft near the engine, engages a final ring gear mounted on a differential case of a differential gearing. While rotating, the final ring gear scoops up transmission oil inside the transmission case, and sends the oil to lubricating devices which supply oil to the input and counter gears. Each input and counter gear is equipped with a lubricating device.
Examples of this type of transmission lubricating device are disclosed in Japanese Utility Model Laid-Open Publication Number 5-10856 and Japanese Utility Model Laid-Open Publication Number 5-8120. Japanese Utility Model Laid-Open Publication Number 5-10856 discusses a transmission in which the differential gear case is integrated with the transmission case. An oil guide on the side of a differential drive gear guides the transmission oil scooped up by the differential drive gear to the upper portion of the differential gear case. An oil tank stores the oil received from the oil guide. The change gear and bearings can be adequately lubricated, and the surface of oil in storage in the differential gear case during driving can be lowered.
Japanese Utility Model Laid-Open Publication Number 5-8120 describes a transmission lubricating device wherein a speed change gear, located on the lower part of the transmission case, always remains engaged. An oil guide on the side of speed change gear guides transmission oil scooped up by the speed change gear to the upper part of transmission case. The guided transmission oil flows through an oil pathway into an oil supply pathway formed in the core of gear shift. The oil surface of the transmission oil in storage can be lowered, and the speed change gear and bearings remain adequately lubricated.
However, with the transmission lubricating device of the prior art, an oil pump and many pipes are necessary to supply transmission oil to each speed gear. Mechanical energy losses are large when the oil pump is driven, thereby reducing fuel efficiency. The transmission's cost is high due to the pump and the pipes, but also due to the large amount of space necessary for the layout.